A comparison of the early development of ischemic brain damage in normoglycemic and hyperglycemic rats using magnetic resonance imaging

The early evolution of ischemic brain injury under normoglycemic and streptozotocin-induced hyperglycemic plasma conditions was studied using magnetic resonance imaging (MRI). Male Sprague-Dawley rats were subjected to either permanent middle cerebral artery occlusion (MCAO), or 1-h MCAO followed by reperfusion using the intraluminal suture insertion method. The animals were divided into four groups each with eight rats: normoglycemia with permanent MCAO, normoglycemia with 1-h MCAO, hyperglycemia with permanent MCAO, and hyperglycemia with 1-h MCAO. Diffusion-weighted images (DWIs) and T2-weighted images (T2WIs) were aquired every l h from 20 min until 6 h after MCAO, at which time cerebral plasma volume images (PVIs) were acquired. Tissue infarction was determined by triphenyltetrazolium chloride staining at 7 h after MCAO. The ischemic damage, measured as the area of DWI and T2WI hyperintensity and tissue infarction, increased significantly in hyperglycemic rats in both permanent and transient MCAO models. In the permanent MCAO model, the maximal apparent water diffusion coefficient (ADC) decline under either normoor hyperglycemia was about 40%, but the speed of ADC drop was faster in hyperlgycemic rats than in normoglycemic rats. Reperfusion after l h of MCAO in normoglycemic rats partly reversed the decline in ADC, whereas the low ADC area continued to expand after reperfusion in the hyperlgycemic group. Between the two hyperglycemic groups with either permanent MCAO or reperfusion, no significant difference was found in the infarct volume measured at 7 h after MCAO. However, reperfusion dramatically increased the extent and accelerated the development rate of vasogenic edema. ADC in the hyperglycemic reperfusion group also dropped to a lower level. A large no-reflow zone was found in the ischemic hemisphere in the hyperglycemic reperfusion group. This study provides strong evidence to support that preischemic hyperglycemia exacerbates ischemic damage in both transient and permanent MCAO models and demonstrates, using MRI, that reperfusion under preischemic hyperglycemia accelerates the evolution of early ischemic injury.     

辣椒素受体拮抗剂AMG517在小鼠脑缺血/再灌注损伤中通过调节炎症因子释放发挥神经保护作用#br#

目的 观察辣椒素受体(TRPV1)拮抗剂AMG517在小鼠脑缺血/再灌注损伤中的作用及相关机制。方法 40只雄性C57BL/6小鼠随机分为假手术组(sham,n=10)、赋形剂（vehicle）+缺血/再注灌注组(vehicle,n=10)、辣椒素+缺血/再注灌注组(capsaicin,n=10)和AMG517+缺血/再注灌组(AMG517,n=10)。采用大脑中动脉闭塞(MCAO)诱导缺血/再灌注损伤,再灌注72 h进行神经行为学评分;同时检测各组小鼠梗死体积、脑水肿、TRPV1 mRNA表达和血清肿瘤坏死因子-α(TNF-α)浓度及白细胞介素-10(IL-10)浓度。结果 与vehicle组相比,AMG517显著减小鼠脑梗死体积(P<0.01)。AMG517给药后也可显著降低小鼠神经行为学评分(P<0.01)。与sham组比较,vehicle组TRPV1 mRNA表达显著增加(P<0.01)。AMG517给药后可显著增加抗炎性细胞因子IL-10浓度,并降低炎性细胞因子TNF-α浓度(P<0.05)。结论 AMG517可改善小鼠缺血/再灌注损伤,可能是通过缓解炎症发挥神经保护作用。     

Comparison between coated vs. uncoated suture middle cerebral artery occlusion in the rat as assessed by perfusion/diffusion weighted imaging

Differences among models in the temporal evolution of ischemia after middle cerebral artery occlusion (MCAO) in rats may considerably influence the results of experimental treatment studies. Using diffusion and perfusion imaging, we compared the spatiotemporal evolution of ischemia in Sprague-Dawley rats after permanent MCAO (pMCAO) with different types of sutures. Male Sprague-Dawley rats were randomly assigned to pMCAO produced with either 4-0 silicone coated (n=8), or 3-0 uncoated monofilaments (n=8). Serial determination of quantitative cerebral blood flow (CBF) and apparent diffusion coefficient (ADC) maps were performed up to 3 h after pMCAO. Lesion volumes were calculated by using previously validated thresholds and correlated with infarct volume corrected for edema defined by 2,3,5-triphenyltetrazolium chloride (TTC) staining at 24 h after MCAO. The ADC/CBF-defined mismatch volume in the 4-0 coated suture model was present significantly longer (up to 120 min) compared to the uncoated 3-0 suture model (30 min). The TTC-derived infarct volume was significantly larger in the coated model (290.3+/-32.8 mm(3)) relative to the uncoated model (252.3+/-34.6 mm(3)). This study demonstrates that the type of suture may significantly influence the spatiotemporal evolution of the ADC/CBF-mismatch as well as the final infarct volume. These inter-model variations must be taken into account when assessing new therapeutic approaches on ischemic lesion evolution in the rat MCAO model.     

小鼠脑缺血时自噬相关基因5的抗损伤作用

 目的: 观察自噬相关基因5(Atg5)在小鼠脑缺血再灌注损伤中的抗损伤作用。方法: 将雄性BALB/c小鼠随机分为假手术(sham)组、缺血再灌注(I/R)组、Atg5 siRNA组和control siRNA组。I/R组采用大脑中动脉阻塞(MCAO)60 min后再灌注24 h。Atg5 siRNA组和control siRNA组将5 μL Atg5 siRNA或scrambled siRNA在MCAO前24 h侧脑室注射。实时荧光定量PCR和Western blot检测Atg5的表达;2,3,5-氯化三苯基四氮唑(TTC)染色法检测抑制Atg5对缺血再灌注损伤后脑梗死面积和水肿率的影响;神经行为学评分法检测抑制Atg5对缺血再灌注损伤后神经症状的影响。结果: MCAO后再灌24 h,缺血半影区Atg5 mRNA和蛋白水平显著增高(P<0.05);Atg5 siRNA明显降低缺血再灌后Atg5 mRNA和蛋白的表达(P<0.05);侧脑室给予Atg5 siRNA能显著增加脑梗死面积和水肿率,并加重神经行为学损伤(P<0.05)。结论: 沉默Atg5加重小鼠脑缺血再灌损伤,提示MCAO后诱导的 Atg5 可减轻小鼠局灶性脑缺血再灌注损伤。     

Extension of the neuroprotective time window for thiazolidinediones in ischemic stroke is dependent on time of reperfusion

Stroke is a leading cause of death and disability but has limited therapeutic options. Thiazolidinediones (TZDs), agonists for the nuclear receptor, peroxisome proliferator-activated receptor (PPAR)γ, reduce infarct volume and improve neurologic function following transient middle cerebral artery occlusion (MCAO) in rats. Translation of these findings into clinical therapy will require careful assessment of dosing paradigms and effective time windows for treatment. Understanding the mechanisms by which TZDs protect the brain provides insight into how time windows for neuroprotection might be extended. We find that two TZDs, pioglitazone and rosiglitazone, significantly reduce infarct volume at doses similar to those used clinically (1 mg/kg for pioglitazone and 0.1 mg/kg for rosiglitazone). We also find that pioglitazone reduces infarction volume in a transient, but not a permanent MCAO model suggesting that reperfusion plays an important role in TZD mediated neuroprotection. Since PPARγ agonists reduce inflammation and oxidative stress, both of which are exacerbated by reperfusion, we hypothesized that TZDs would be most effective if administered prior to reperfusion. We administered TZDs 3 h after MCAO and found that infarction volume and neurologic function are significantly improved in animals reperfused at 3 h and 15 min (after TZD treatment), but not in animals reperfused at 2 h (before TZD treatment) when assessed either 24 h or 3 weeks after MCAO. While TZDs reduce intercellular adhesion molecule (ICAM) expression to a similar extent regardless of the time of reperfusion, leukocyte entry into brain parenchyma is more dramatically reduced when reperfusion is delayed until after drug treatment. The finding that delaying reperfusion until after TZD treatment is beneficial despite a longer period of ischemia, is dramatic given the widely held view that duration of ischemia is the most important determinate of injury.     

缺血后适应对大鼠脑缺血/再灌注损伤的影响

目的：探讨缺血后适应对大鼠脑缺血/再灌注损伤的影响。方法:应用线栓法制作大鼠脑缺血/再灌注损伤模型；21只雄性SD大鼠随机分为缺血/再灌注组、夹闭单侧颈总动脉后处理组和夹闭双侧颈总动脉后处理组，每组7只。再灌注48 h，测定脑梗死体积；拔栓后1 h及处死大鼠前进行神经功能测定；梗死即刻、梗死后10 min、术中1 h、拔栓后即刻、每次夹/松颈总动脉时、干预后30 min等15个时点监测脑血流。结果:夹闭单侧、双侧颈总动脉后处理组大鼠脑组织梗死体积与缺血/再灌注组相比明显减小，有显著差异；3组脑血流各个时点方差分析差异无显著，但是夹闭双侧颈总动脉后处理组干预30 min后脑血流百分比较缺血/再灌注组、夹闭单侧颈总动脉后处理组降低9％。手术后1 h 3组神经功能评分P<0.05，差异显著，夹闭单侧、双侧颈总动脉后处理组神经功能缺损均比缺血/再灌注组减轻。结论:缺血后适应能够明显减小梗塞体积，改善大鼠术后1h神经功能评分，可能与缺血后适应调节早期再灌注时血流动力学状态有关。     

Zinc translocation accelerates infarction after mild transient focal ischemia

Excess release of chelatable zinc (Zn(2+)) from central synaptic vesicles may contribute to the pathogenesis of selective neuronal cell death following transient forebrain ischemia, but a role in neurodegeneration after focal ischemia has not been defined. Adult male Long-Evans rats subjected to middle cerebral artery occlusion (MCAO) for 30 min followed by reperfusion developed delayed cerebral infarction reaching completion 3 days after the insult. One day after the insult, many degenerating cerebral neurons exhibited increased intracellular Zn(2+), and some labeled with the antibody against activated caspase-3. I.c.v. administration of the Zn(2+) chelator, EDTA saturated with equimolar Ca(2+) (CaEDTA), 15 min prior to ischemia attenuated subsequent Zn(2+) translocation into cortical neurons, and reduced infarct volume measured 3 days after ischemia. Although the protective effect of CaEDTA at this endpoint was substantial (about 70% infarct reduction), it was lost when insult severity was increased (from 30 to 60 min MCAO), or when infarct volume was measured at a much later time point (14 days instead of 3 days after ischemia).These data suggest that toxic Zn(2+) translocation, from presynaptic terminals to post-synaptic cell bodies, may accelerate the development of cerebral infarction following mild transient focal ischemia.     

Ghrelin对脑缺血再灌注大鼠脑水肿和水通道蛋白4表达的影响

 目的： 探讨ghrelin对脑缺血再灌注大鼠脑水肿、血脑屏障通透性及水通道蛋白4（AQP4）表达的影响。方法： 成年SD雄性大鼠随机分为3组:sham组、大脑中动脉阻塞（MCAO）组和ghrelin处理组。采用线栓法复制MCAO模型（缺血2 h,再灌注22 h）。Ghrelin组大鼠于再灌开始时经股静脉注射ghrelin 10 nmol/kg。TTC染色观察脑梗死体积,神经功能评分判断脑功能障碍程度,分别以体积计算和干湿重法检测脑肿胀程度和脑含水量的变化,收集脑血管外伊文思蓝(EB)来评估血脑屏障的破坏程度,免疫组化和Western blotting检测AQP4的表达变化。结果： 与MCAO组比较,ghrelin处理组的脑梗死体积较小（P<0.01）,神经功能评分较低（P<0.01）,脑组织中的EB渗出量较少（P<0.01）。Ghrelin处理组大鼠的脑肿胀体积、脑含水量和AQP4表达明显低于MCAO组（P<0.05）。结论： Ghrelin减轻大鼠脑缺血/再灌注损伤,减轻脑水肿和血脑屏障的破坏,抑制脑组织中AQP4的表达。AQP4在ghrelin的脑保护机制中可能发挥重要作用。     

磁共振扩散加权成像对兔脑缺血再灌注伤的评价

目的探讨兔脑缺血再灌注后磁共振扩散加权成像（DWI）的特点。方法将成年新西兰兔用线栓法建立兔大脑中动脉闭塞再灌注（MCAO／R）模型,再将成功的兔MCAO／R模型随机分为永久性缺血组和缺血再灌注组;另取同样动物行假手术分别作为缺血组及再灌注组的对照组;观察不同时间DWI像上高信号区范围变化及表观扩散系数（ADC）的演变特点。结果1．缺血组：缺血1h可见到DWI像上明显的高信号伴ADC值的下降,缺血不同时间点DWI像上的高信号区较缺血1h均有增大,24h后趋于稳定。缺血组不同时间点平均ADC值呈先下降后上升的趋势。2．再灌注组：与再灌注前相比,再灌注2h、5h组均表现为DWI像上高信号区缩小及ADC值升高;再灌注11h组表现为高信号范围增大伴ADC值升高;再灌注23h、47h组表现为高信号范围增大而ADC值出现较明显下降。结论急性脑缺血后DWI像高信号区及ADC值的下降经早期再灌注后可明显改善,但持续再灌注可能导致ADC值再次下降。     

局灶性脑缺血预处理上调大鼠梗死区周围巢蛋白的表达

目的 观察局灶性脑缺血预处理(IP)对巢蛋白(NESTIN)表达的影响,探讨NESTIN与脑缺血耐受(BIT)的关系及可能的内源性神经保护机制.方法 45只SD雄性大鼠随机分为脑缺血预处理(CIP)组、大脑中动脉阻塞(MCAO)组、假手术(sham)组.采用TTC染色测定脑梗死体积,光镜下观察脑组织病理改变,免疫组织化...     

Diffusion- and perfusion-weighted MR imaging of transient focal cerebral ischaemia in mice

Temporary focal ischaemia was induced in wild-type C57Black/6 mice by thread occlusion of the middle cerebral artery (MCA). Recirculation was started after 60 min and maintained for 24 h, after which the mouse brain was frozen in situ. Development of the cerebral infarct was monitored by diffusion-, perfusion- and T(2)-weighted magnetic resonance imaging (MRI) during ischaemia, during the early reperfusion period of 90 min, and at 24 h after reperfusion. Ischaemia caused a marked reduction of the perfusion signal intensity and of the apparent diffusion coefficient (ADC) of tissue water in the ipsilateral MCA territory. In sham-operated control animals ADC remained unchanged. Hemispheric lesion volume after 1 h MCA occlusion was 53 +/- 6% (n = 6), as defined by an ADC decrease of more than 20%. Recirculation reduced hemispheric lesion volume to only 27 +/- 13%, while there was a trend towards secondary lesion growth at 24 h. Post-ischaemic recovery of perfusion was slow, heterogeneous and incomplete. A region-of-interest analysis showed only partial and transient recovery of the ADC, particularly in the dorsolateral cortex and lateral caudate putamen, which may be explained by inadequate reperfusion in these regions. Detailed MRI studies of cerebral ischaemia and reperfusion may now also be performed in the transgenic mice.     

肢体缺血后适应对小鼠脑缺血再灌注损伤的影响及机制

目的:建立小鼠脑缺血后进行短暂肢体缺血提高脑缺血耐受模型,确定肢体缺血后适应对脑缺血时程的影响及热休克蛋白70(HSP70)的作用,探讨肢体缺血后适应(LIPostC)对脑缺血/再灌注损伤抑制作用和机制。方法:复制小鼠大脑中动脉闭塞模型(MCAO),第1批实验将小鼠分为9组:假手术组、脑缺血/再灌注组(缺血时间分别0.5 h、1 h、1.5 h、2 h组),脑缺血/再灌注+短暂肢体缺血(LIPostC)组(0.5 h+LIPostC、1 h+LIPostC、1.5 h+LIPostC、2 h+LIPostC组)。分别观察小鼠运动行为变化;TTC染色测量脑梗死体积;HE染色观察脑组织损伤程度;TUNEL法检测神经元凋亡程度。第2批实验将小鼠随机分为4组:假手术组、脑缺血/再灌注组、MCAO+LIPostC组和MCAO+LIPostC+quercetin组(缺血时间为2 h)。术后24 h用Western blotting法检测脑皮质中HSP70蛋白表达和神经功能评分。结果:脑缺血时程影响小鼠运动行为和脑损伤程度,随脑缺血时间延长,小鼠的脑再灌注损伤程度加重,其行为缺陷和脑病理变化明显;缺血2 h组脑损伤程度比缺血1.5 h组和缺血1 h组严重(P0.05)。脑缺血后不同时间施加LIPostC显示不同程度的神经保护作用。LIPostC各组与相对应的I/R组比较,其脑再灌注损伤程度呈现不同程度减轻,行为学评分降低、脑梗死体积减小,脑皮质损伤减轻,TUNEL阳性凋亡细胞数目减少。脑缺血2 h再灌注损伤较重,但LIPostC仍具有明显的脑保护作用。以2 h脑缺血小鼠为模型进行机制研究,结果表明,LIPostC可提高缺血脑组织HSP70蛋白表达,改善神经功能,HSP70抑制剂quercetin可削弱LIPostC的这种脑保护作用。结论:LIPostC可抑制MCAO小鼠的脑缺血再灌注损伤,促进缺血脑区HSP70表达和改善神经功能。HSP70在LIPostC提高MCAO小鼠的脑缺血耐受机制中发挥重要作用。     

Attenuation of edema and infarct volume following focal cerebral ischemia by early but not delayed administration of a novel small molecule KDR kinase inhibitor

Vascular endothelial growth factor (VEGF) may mediate increases in vascular permeability and hence plasma extravasation and edema following cerebral ischemia. To better define the role of VEGF in edema, we examined the effectiveness of a novel small molecule KDR kinase inhibitor Compound-1 in reducing edema and infarct volume following focal cerebral ischemia in studies utilizing treatment regimens initiated both pre- and post-ischemia, and with study durations of 24-72 h. Rats were subjected to 90 min of middle cerebral artery occlusion (MCAO) followed by reperfusion. Pretreatment with Compound-1 (40 mg/kg p.o.) starting 0.5h before occlusion significantly reduced infarct volume at 72 h post-MCAO (vehicle, 194.1+/-22.9 mm(3) vs. Compound-1, 127.6+/-22.8mm(3) and positive control MK-801, 104.4+/-22.6mm(3), both p<0.05 compared to vehicle control), whereas Compound-1 treatment initiated at 2h after occlusion did not affect infarct volume. Compound-1 pretreatment also significantly reduced brain water content at 24h (vehicle, 80.3+/-0.2% vs. Compound-1, 79.7+/-0.2%, p<0.05) but not at 72 h after MCAO. These results demonstrate that early pretreatment administration of a KDR kinase inhibitor elicited an early, transient decrease in edema and subsequent reduction in infarct volume, implicating VEGF as a mediator of stroke-related vascular permeability and ischemic injury.     

糖尿病大鼠 局灶脑缺血／再灌注损伤与脑组织TGF—β1mRNA表达

目的：观察糖尿病和对照组鼠脑缺血/再灌注损伤与转化生长因子β1（TGF-β1）mRNA表达的异质性。方法：采用逆转录聚合酶链式反应（RT-PCR）检测大鼠中脑动脉阻塞（MCAO）后脑内TGF-β1mRNA表达水平,并且应用组织病理进行损伤程度评定。结果：糖尿病组大鼠脑缺血及缺血/再灌损伤程度明显重于“相应对照组”。糖尿病及对照组大鼠在MCAO2h时TGF-β1mRNA表达量明显增高,后者增高比前者更为明显。再灌24h后TGF-β1mRNA表达量下降,但仍高于假手术组。结论：糖尿病加重缺血/再灌性脑损伤;MCAO后TGF-β1mRNA表达增高可能有是机体一种抗损伤反应,糖尿病组抗损伤反应下降。     

Evolution of apparent diffusion coefficient and transverse relaxation time (T2) in the subchronic stage of global cerebral oligemia in different rat models

Using magnetic resonance imaging techniques, we examined the time course of apparent diffusion coefficient (ADC), T2, and T2* relaxation times in 1-year-old rats after different forms of cerebral oligemia had been induced by (1) transient systemic hypotension, (2) permanent bilateral carotid artery occlusion (BCCAO), and (3) combined hypotension and BCCAO over a time period of 14 days after the oligemic event. These groups were compared with a group of sham-operated adult rats (controls, 4) to rule out a drift of the parameters over time. The animals were examined in a 2.35 T scanner. ADC, T2, and T2* were measured in both hemispheres of rat parietotemporal cerebral cortex, thalamic nuclei, and hippocampus 1 day before as well as on days 1, 3, 7, and 14 after sham operation and in different models of oligemia, respectively. Hypotension alone had no significant effect on MRI parameters in rat brain. After BCCAO, an increase in T2* was observed. If a permanent BCCAO was combined with transient hypotension, however, 84% of 1-year-old animals died within 14 days after surgery. In the surviving animals, significant changes in ADC, T2, and T2* were observed in the hippocampus and parietotemporal cerebral cortex. ADC showed a decrease on day 1 after oligemia, and an increase on days 3, 7, and 14. The T2* and T2 values were markedly increased on days 7 and 14 after surgery. In conclusion, only severe oligemia combining BCCAO and hypotension induces significant changes in tissue integrity (as shown by ADC) and in blood oxygenation levels in the subchronic period, whereas no significant changes were detected if permanent BCCAO or transient hypotension was applied separately.     

X线照射增加大鼠心肌对缺血/再灌注损伤的敏感性*

 目的：观察胸部X线放射治疗大鼠对心肌缺血/再灌注损伤的敏感性。方法：用胸部单次照射X线20 Gy构建放射性心脏损伤模型,采用完全随机分组方法将Wistar大鼠分为假损伤组、损伤组、假损伤+假手术组、假损伤+缺血/再灌注组、损伤+假手术组和损伤+缺血/再灌注组,于创伤后2周行心肌缺血/再灌注。通过BL-410生物信号记录分析系统记录各组大鼠左心室发展压（LVDP）、左心室压力上升的最大速率（+dp/dtmax）和左心室压力下降的最大速率（-dp/dtmax）;采用ELISA方法检测大鼠血清心肌肌钙蛋白I（cTnI）和肌酸激酶同工酶（CK-MB）;用BI2000图像分析软件测定心肌梗死面积占总面积的百分比。结果：损伤+缺血/再灌注组离体心功能明显低于假损伤+缺血/再灌注组（P＜0.01）,损伤+缺血/再灌注组血清cTnI和CK-MB水平显著高于假损伤+缺血/再灌注组（P＜0.01）,损伤+缺血/再灌注组心肌梗死面积显著大于假损伤+缺血/再灌注组（P＜0.01）。结论:X线照射增加大鼠心肌对缺血/再灌注损伤的敏感性。     

Alpha-melanocyte stimulating hormone suppresses intracerebral tumor necrosis factor-alpha and interleukin-1beta gene expression following transient cerebral ischemia in mice

Following stroke, an intracerebral inflammatory response develops that may contribute to postischemic central nervous system injury. This study's objective was to determine whether the anti-inflammatory neuropeptide alpha-melanocyte stimulating hormone (MSH) can suppress postischemic activation of intracerebral tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) gene expression. Ipsilateral TNF-alpha levels were increased in cerebrocortical territory of the middle cerebral artery (MCA) following transient unilateral MCA occlusion (MCAO) and reperfusion in mice, and systemic alpha-MSH treatment (0.5 mg/kg i.p.) suppressed this increase. Systemic alpha-MSH treatment also inhibited the marked increases in cortical TNF-alpha and IL-1beta mRNA levels following MCAO, and reduced the intracerebral TNF-alpha protein levels seen after transient global ischemia. We conclude that alpha-MSH treatment suppresses intracerebral proinflammatory cytokine gene expression following transient cerebral ischemia, suggesting that systemically administered melanocortins may exert neuroprotective effects in cerebral ischemia.     

Neuroprotective properties of prostaglandin I2 IP receptor in focal cerebral ischemia

We and others have identified that inhibition of cyclooxygenase might not be the optimal approach to limiting brain damage after stroke. Now we are investigating the unique properties of the various prostaglandin receptors to determine whether blocking those that mediate toxicity or stimulating those that reduce toxicity will improve neurological outcomes. Here, we determined the respective contribution of the prostaglandin I₂ (PGI₂) receptor in transient middle cerebral artery (MCA) occlusion (tMCAO) and permanent MCAO (pMCAO) preclinical stroke models by using male wildtype (WT) and IP receptor knockout (IP^−/−) C57Bl/6 mice. In addition, we investigated the putative preventive and therapeutic effects of the IP receptor agonist beraprost. The infarct volumes and neurological deficit scores (NDS) were significantly greater in IP^−/− than in WT mice after both tMCAO and pMCAO. Interestingly, beraprost pretreatment (50 or 100 μg/kg p.o.) 30 min before tMCAO and post-treatment (100 μg/kg p.o.) at 2 or 4.5 h of reperfusion significantly reduced the neurological deficit score and infarct volume in WT mice. Post-treatment with beraprost (100 μg/kg p.o.) 4.5 h after pMCAO also significantly decreased neurological deficits and infarct volume in WT mice. Together, these novel findings suggest for the first time that PGI₂ IP receptor activation can attenuate anatomical and functional damage following ischemic stroke.     

Lipocalin-prostaglandin D synthase is a critical beneficial factor in transient and permanent focal cerebral ischemia

Prostaglandin D₂ (PGD₂) is the most abundant prostaglandin produced in the brain. It is a metabolite of arachidonic acid and synthesized by prostaglandin D₂ synthases (PGDS) via the cyclooxygenase pathway. Two distinct types of PGDS have been identified: hematopoietic prostaglandin D synthase (H-PGDS) and lipocalin-type prostaglandin D synthase (L-PGDS). Because relatively little is known about the role of L-PGDS in the CNS, here we examined the outcomes in L-PGDS knockout and wild-type (WT) mice after two different cerebral ischemia models, transient middle cerebral artery (MCA) occlusion (tMCAO) and permanent distal middle cerebral artery occlusion (pMCAO). In the tMCAO model, the MCA was occluded with a monofilament for 90 min and then reperfused for 4 days. In the pMCAO model, the distal part of the MCA was permanently occluded and the mice were sacrificed after 7 days. Percent corrected infarct volume and neurological score were determined after 4 and 7 days, respectively. L-PGDS knockout mice had significantly greater infarct volume and brain edema than did WT mice after tMCAO (P<0.01). Similarly, L-PGDS knockout mice showed greater infarct volume and neurological deficits as compared to their WT counterparts after pMCAO (P<0.01). Using the two models enabled us to study the role of L-PGDS in both early (tMCAO) and delayed (pMCAO) ischemic processes. Our findings suggest that L-PGDS is beneficial for protecting the brain against transient and permanent cerebral ischemia. These results provide a better understanding of the role played by the enzymes that control eicosanoid synthesis and how they can be utilized as potential targets to prevent damage following either acute or potentially chronic neurological disorders.     

Intravenous administration of thioredoxin decreases brain damage following transient focal cerebral ischemia in mice

Thioredoxin (TRX) is induced by a variety of oxidative stimuli and shows cytoprotective roles against oxidative stress. To clarify the possibility of clinical application, we examined the effects of intravenously administered TRX in a model of transient focal cerebral ischemia in this study. Mature male C57BL/6j mice received either continuous intravenous infusion of recombinant human TRX (rhTRX) over a range of 1-10 mg/kg, bovine serum albumin, or vehicle alone for 2 h after 90-min transient middle cerebral artery occlusion (MCAO). Twenty-four hours after the transient MCAO, the animals were evaluated neurologically and the infarct volumes were assessed. Infarct volume, neurological deficit, and protein carbonyl contents, a marker of protein oxidation, in the brain were significantly ameliorated in rhTRX-treated mice at the dose of 3 and 10 mg/kg versus these parameters in control animals. Moreover, activation of p38 mitogen-activated protein kinase, whose pathway is involved in ischemic neuronal death, was suppressed in the rhTRX-treated mice. Further, rhTRX was detected in the ischemic hemisphere by western blot analysis, suggesting that rhTRX was able to permeate the blood-brain barrier in the ischemic hemisphere. These data indicate that exogenous TRX exerts distinct cytoprotective effects on cerebral ischemia/reperfusion injury in mice by means of its redox-regulating activity.